Wasilewski is a right back. Despite being a defensive player, Wasilewski often scores goals. During the 2008–09 season, he was Anderlecht's third most prolific goalscorer, tied with Guillaume Gillet at 8 goals.

On 30 August 2009, Wasilewski suffered an open leg fracture in the 24th minute of the 1–1 Jupiler League draw between Anderlecht and Standard Liège when Liège's Axel Witsel made a challenge. Witsel was red carded for the offence. Wasilewski underwent corrective surgery for open fractures to both the tibia and fibula. Witsel was suspended for 8 games by the Belgian FA over the incident, after an appeal.[3]

After a long rehabilitation, Wasilewski made his return on 8 May 2010.[4] Wasilewski celebrated his return to Anderlecht's first eleven with the opening goal of his side's 2–1 win at SV Zulte Waregem.

His drive to return was rewarded with a new contract until the summer of 2013, with the club talking about him as "a club monument, who had to deliver an inhuman battle". [5]

Wasilewski and Witsel, now at Zenit St. Petersburg, met again on the field on 24 October 2012 in a UEFA Champions League group match. Wasilewski announced in advance that he will refuse to shake hands with Witsel before the game, with Anderlecht management accepting his decision.[6] However, he ultimately changed his mind and accepted Witsel's hand, claiming that he didn't want to turn the atmosphere of the match into a personal duel.[7] Zenit won the game 1–0.

On 14 September 2013, Marcin Wasilewski was reported to be on trial with Leicester City in the English Championship, in the hope of landing a contract.[8] On 17 September Wasilewski was confirmed as signing for The Foxes on a one year contract.[9] He made his debut in a League Cup third round match against Derby County on 24 September, playing the entire match as Leicester won 2–1.[10] On 30 November 2013, a coach-full of Anderlecht fans travelled to Leicester's King Power Stadium to support Marcin at his new club.[11] There were emotional scenes after Marcin played a key role in City's 3–0 win over Millwall.[11] Wasilewski established himself as a first-team regular as Leicester finished the season as Championship champions and secured their return to the Premier League. On 22 May 2014, Wasilewski extended his contract by a further year.